This invention relates to disinfecting and/or cleaning lenses, such as contact lenses. In particular, the invention relates to compositions and methods useful to quickly and effectively disinfect and/or clean lenses while reducing eye irritation caused by disinfecting the lenses.
Contact lenses should be periodically cleaned and disinfected by the user to prevent infection or other deleterious effects on ocular health which may be associated with contact lens wear. Currently, there are several different conventional systems and methods which enable the user to clean and disinfect their contact lenses between wearing times. These conventional cleaning and disinfection systems can be divided into "hot" and "cold" systems. Hot systems require the use of heat to disinfect the contact lenses, whereas cold systems use chemical disinfectants at ambient temperatures to disinfect the lenses.
Within the realm of cold disinfection systems are hydrogen peroxide disinfection systems. Disinfecting hydrogen peroxide solutions are effective to kill the bacteria and fungi which may contaminate contact lenses. However, residual hydrogen peroxide on a disinfected contact lens may cause irritation, burning or trauma to the eye unless this hydrogen peroxide is destroyed, i.e., decomposed, neutralized, inactivated or chemically reduced. Therefore, destruction of the residual hydrogen peroxide in the liquid medium containing the disinfected contact lens is needed to enable safe and comfortable wear of the disinfected contact lens.
Associated with the problem of hydrogen peroxide destruction in contact lens disinfection systems are the problems of easy use and user compliance. To enhance user compliance and ease of use, several efforts have focused on one-step disinfection and hydrogen peroxide destruction. In this regard, various time release tablets containing a core tablet including a hydrogen peroxide destroying component, e.g., a hydrogen peroxide reducing agent, and having a delayed release coating on the core tablet have been suggested. The delayed release coating is necessary in these compositions because the hydrogen peroxide destroying components used provide very rapid, or kinetically fast, destruction of hydrogen peroxide. Thus, the delayed release coating allowed sufficient time for the hydrogen peroxide to disinfect the contact lens before the residual hydrogen peroxide was destroyed.
Such delayed release coatings are subject to various problems. First, the amount of time the release is delayed depends on the composition of the coating and the amount of the coating. In mass producing the coated tablets, each of these parameters may vary over a considerable range so that the final coating may not provide the intended delayed release. Thus, the lens may not be completely or effectively disinfected before the disinfectant is destroyed, or the disinfectant may still be present when the lens is put back into the eye, thus resulting in eye irritation or worse. In addition, the coating itself often becomes part of the disinfectant solution and may, by its nature, cause eye irritation.
There continues to be a need for a contact lens care system which rapidly and effectively disinfects, and preferably cleans, a contact lens so that the disinfected lens can be safely and comfortably worn.